Comparison of different drug regimens for the treatment of loiasis - A TropNet retrospective study.

The few cases of loiasis reported every year from non-endemic countries, especially Europe and North America, are often of limited interest. Case series reported in Western countries revealed a wide heterogeneity of treatment and follow-up patterns over the last three decades, highlighting that the management of imported loiasis needs standardization. Currently, three drugs are recommended for the treatment of loiasis: dietylcarbamazine (DEC), albendazole (ALB), and ivermectin (IVM). DEC is the drug of choice because of its macro- and microfilaricidal activity, that can cause a rapid decrease in the loa microfilaremia, although sometimes multiple courses of DEC are required to achieve clinical and parasitological cure. Moreover, this drug is not available in several countries; for instance, the drug is currently only available at 25/69 TropNet sites, can be ordered and be available in a few days at 11/69 sites and is neither available nor orderable at 33/69 sites. Ivermectin has a marked microfilaricidal effect (Loa microfilaremia decreases by 70–80% within the first 3 days after a single dose of 150 µg/kg) , but probably is not active on macrofilariae. Short courses of ALB have little effect on loa loa, but when given at a dose of 200 mg twice a day for 21 days, the drug has probably an embryotoxic effect (i.e., it interrupts embryogenesis in the uteri of the adult female worms), and perhaps also a macrofilaricidal effect.

In conclusion, definitive cure of loa infection can sometimes be difficult and this is all the more true because DEC is not widely available. A randomized controlled trial comparing different drugs in non-endemic countries is not feasible for the small number of cases diagnosed. So, this study aims at assessing retrospectively the outcome of patients treated with different regimens based on the following drugs: DEC, ALB, IVM.